{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T18:57:58Z","timestamp":1782845878777,"version":"3.54.5"},"reference-count":39,"publisher":"JMIR Publications Inc.","issue":"11","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["JMIR Public Health Surveill"],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>A possible link between influenza immunization and susceptibility to the complications of COVID-19 infection has been previously suggested owing to a boost in the immunity against SARS-CoV-2.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Objective<\/jats:title>\n                    <jats:p>This study aimed to investigate whether individuals with COVID-19 could have benefited from vaccination against influenza. We hypothesized that the immunity resulting from the previous influenza vaccination would boost part of the immunity against SARS-CoV-2.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>We performed a population-based cohort study including all patients with COVID-19 with registered entries in the primary health care (PHC) electronic records during the first wave of the COVID-19 pandemic (March 1 to June 30, 2020) in Catalonia, Spain. We compared individuals who took an influenza vaccine before being infected with COVID-19, with those who had not taken one. Data were obtained from Information System for Research in Primary Care, capturing PHC information of 5.8 million people from Catalonia. The main outcomes assessed during follow-up were a diagnosis of pneumonia, hospital admission, and mortality.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>We included 309,039 individuals with COVID-19 and compared them on the basis of their influenza immunization status, with 114,181 (36.9%) having been vaccinated at least once and 194,858 (63.1%) having never been vaccinated. In total, 21,721 (19%) vaccinated individuals and 11,000 (5.7%) unvaccinated individuals had at least one of their outcomes assessed. Those vaccinated against influenza at any time (odds ratio [OR] 1.14, 95% CI 1.10-1.19), recently (OR 1.13, 95% CI 1.10-1.18), or recurrently (OR 1.10, 95% CI 1.05-1.15) before being infected with COVID-19 had a higher risk of presenting at least one of the outcomes than did unvaccinated individuals. When we excluded people living in long-term care facilities, the results were similar.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>We could not establish a protective role of the immunity conferred by the influenza vaccine on the outcomes of COVID-19 infection, as the risk of COVID-19 complications was higher in vaccinated than in unvaccinated individuals. Our results correspond to the first wave of the COVID-19 pandemic, where more complications and mortalities due to COVID-19 had occurred. Despite that, our study adds more evidence for the analysis of a possible link between the quality of immunity and COVID-19 outcomes, particularly in the PHC setting.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.2196\/36712","type":"journal-article","created":{"date-parts":[[2022,10,18]],"date-time":"2022-10-18T05:46:47Z","timestamp":1666072007000},"page":"e36712","source":"Crossref","is-referenced-by-count":6,"title":["Outcomes of COVID-19 Infection in People Previously Vaccinated Against Influenza: Population-Based Cohort Study Using Primary Health Care Electronic Records"],"prefix":"10.2196","volume":"8","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3750-9233","authenticated-orcid":false,"given":"Maria","family":"Giner-Soriano","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6870-3533","authenticated-orcid":false,"given":"Vanessa","family":"de Dios","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8630-152X","authenticated-orcid":false,"given":"Dan","family":"Ouchi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3780-4996","authenticated-orcid":false,"given":"Carles","family":"Vilaplana-Carnerero","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8839-5056","authenticated-orcid":false,"given":"M\u00f2nica","family":"Monteagudo","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6752-8748","authenticated-orcid":false,"given":"Rosa","family":"Morros","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1010","published-online":{"date-parts":[[2022,11,11]]},"reference":[{"key":"ref1","unstructured":"Coronavirus disease 2019 (\u200eCOVID-19)\u200e: situation report, 51World Health Organization20202022-10-31https:\/\/apps.who.int\/iris\/handle\/10665\/331475"},{"key":"ref2","doi-asserted-by":"publisher","DOI":"10.1111\/eci.13554"},{"key":"ref3","doi-asserted-by":"publisher","DOI":"10.1038\/s41580-021-00418-x"},{"key":"ref4","doi-asserted-by":"publisher","DOI":"10.1016\/j.cmi.2021.05.022"},{"key":"ref5","doi-asserted-by":"publisher","DOI":"10.24875\/BMHIM.20000183"},{"key":"ref6","doi-asserted-by":"publisher","DOI":"10.7554\/eLife.57309"},{"key":"ref7","doi-asserted-by":"publisher","DOI":"10.1038\/srep07027"},{"key":"ref8","doi-asserted-by":"publisher","DOI":"10.1093\/cid\/cis307"},{"key":"ref9","doi-asserted-by":"publisher","DOI":"10.1097\/EDE.0000000000000670"},{"key":"ref10","doi-asserted-by":"publisher","DOI":"10.1016\/j.chest.2020.05.580"},{"key":"ref11","doi-asserted-by":"publisher","DOI":"10.1002\/ddr.21656"},{"key":"ref12","doi-asserted-by":"publisher","DOI":"10.1016\/s1473-3099(20)30162-6"},{"key":"ref13","doi-asserted-by":"publisher","DOI":"10.1016\/j.mbs.2020.108378"},{"key":"ref14","doi-asserted-by":"publisher","DOI":"10.1016\/j.mehy.2020.109752"},{"key":"ref15","doi-asserted-by":"publisher","DOI":"10.1038\/s41591-020-0820-9"},{"key":"ref16","doi-asserted-by":"publisher","DOI":"10.1126\/scitranslmed.aan8405"},{"key":"ref17","doi-asserted-by":"publisher","DOI":"10.2139\/ssrn.3558015"},{"key":"ref18","doi-asserted-by":"publisher","DOI":"10.1016\/j.coviro.2017.11.002"},{"key":"ref19","unstructured":"DepartamentDSGDCPla d\u2019informaci\u00f3 de les infeccions respirat\u00f2ries agudes a CatalunyaBalan\u00e7 temporada gripal18-202022-11-03https:\/\/canalsalut.gencat.cat\/ca\/professionals\/vigilancia-epidemiologica\/pla-dinformacio-de-les-infeccions-respirato ries-agudes-a-catalunya-pidirac\/"},{"key":"ref20","unstructured":"Information system for the development of research in primary careSIDIAP20222022-10-31http:\/\/www.sidiap.org\/index.php\/en"},{"key":"ref21","unstructured":"International Statistical Classification of Diseases and Related Health Problems 10th RevisionICD-10 Version:20192022-10-31https:\/\/icd.who.int\/browse10\/2019\/en"},{"key":"ref22","unstructured":"ATC\/DDD Index 2022WHO Collaborating Centre for Drug Statistics Methodology2022-10-31https:\/\/www.whocc.no\/atc_ddd _index\/"},{"key":"ref23","unstructured":"Conjunt m\u00ednim b\u00e0sic de dades (CMBD)CatSalut. Servei Catal\u00e0 de la Salut2022-10-31http:\/\/catsalut.gencat.cat\/ca\/proveidors -professionals\/registres-catalegs\/registres\/cmbd\/"},{"key":"ref24","unstructured":"COVID-19 - Diagn\u00f2stics APGeneralitat de Catalunya2022-10-31https:\/\/aquas.gencat.cat\/ca\/actualitat\/ultimes-dades-coronavirus\/index.html#googtrans(ca%7Cen)"},{"key":"ref25","unstructured":"Pla d\u2019informaci\u00f3 de les infeccions respirat\u00f2ries agudes a Catalunya (PIDIRAC) 2019-2020Generalitat de Catalunya. Ag\u00e8ncia de Salut P\u00fablica de Catalunya20192022-10-31https:\/\/scientiasalut.gencat.cat\/bitstream\/handle\/11351\/4318\/pla_infor macio_infeccions_respiratories_agudes_catalunya_2019_2020.pdf?sequence=1&isAllowed=y"},{"key":"ref26","doi-asserted-by":"publisher","DOI":"10.1157\/13123961"},{"key":"ref27","unstructured":"Vacunas y Programa de Vacunaci\u00f3nMinisterio de Sanidad2022-10-31https:\/\/www.mscbs.gob.es\/profesionales\/saludPublica\/prevPromocion\/vacunaciones\/programasDeVacunacion\/gripe\/home.htm"},{"key":"ref28","doi-asserted-by":"publisher","DOI":"10.1007\/s10875-020-00925-0"},{"key":"ref29","doi-asserted-by":"publisher","DOI":"10.1007\/s11739-021-02702-2"},{"key":"ref30","doi-asserted-by":"publisher","DOI":"10.1136\/bmjebm-2020-111549"},{"key":"ref31","doi-asserted-by":"publisher","DOI":"10.3390\/ijerph17217870"},{"key":"ref32","unstructured":"Influenza vaccination ratesOrganisation for Economic Co-operation and Development2022-10-31https:\/\/data.oecd.org\/health care\/influenza-vaccination-rates.htm"},{"key":"ref33","doi-asserted-by":"publisher","DOI":"10.1111\/ijcp.14901"},{"key":"ref34","unstructured":"Ag\u00e8nciade Salut P\u00fablica de Catalunya (ASPCAT)Campanya de vacunaci\u00f3 antigripal 2021-2022Vacunaci\u00f3 antigripal2022-11-03https:\/\/canalsalut.gencat.cat\/ca\/professionals\/vigilancia-epidemiologica\/pla-dinformacio-de-les-infeccions-respiratories-agudes-a-catalunya-pidirac\/"},{"key":"ref35","author":"Rothman, K","year":"2008","journal-title":"Modern Epidemiology (3rd edition)"},{"key":"ref36","doi-asserted-by":"publisher","DOI":"10.1093\/aje\/kwp173"},{"key":"ref37","doi-asserted-by":"publisher","DOI":"10.1001\/archinternmed.2011.2238"},{"key":"ref38","doi-asserted-by":"publisher","DOI":"10.1093\/aje\/kwu485"},{"key":"ref39","doi-asserted-by":"publisher","DOI":"10.3390\/healthcare9050522"}],"container-title":["JMIR Public Health and Surveillance"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/publichealth.jmir.org\/2022\/11\/e36712","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,6,30]],"date-time":"2026-06-30T17:59:46Z","timestamp":1782842386000},"score":1,"resource":{"primary":{"URL":"https:\/\/publichealth.jmir.org\/2022\/11\/e36712"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,11,11]]},"references-count":39,"journal-issue":{"issue":"11","published-online":{"date-parts":[[2022]]}},"URL":"https:\/\/doi.org\/10.2196\/36712","relation":{},"ISSN":["2369-2960"],"issn-type":[{"value":"2369-2960","type":"electronic"}],"subject":[],"published":{"date-parts":[[2022,11,11]]}}}